Is x-y+1 greater than x+y-1 ? : GMAT Data Sufficiency (DS)
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# Is x-y+1 greater than x+y-1 ?

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Is x-y+1 greater than x+y-1 ? [#permalink]

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30 Sep 2010, 21:11
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Is x-y+1 greater than x+y-1 ?

(1) x > 0
(2) y < 0
[Reveal] Spoiler: OA

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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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30 Sep 2010, 21:25
Michmax3 wrote:
Is x-y+1 greater than x+y-1

1) x>0
2) y<0

Is x-y+1 > x+y-1

1-y > y-1 => This is possible only if y is negative.

Hence B is sufficient.
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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30 Sep 2010, 21:32
Michmax3 wrote:
Is x-y+1 greater than x+y-1

1) x>0
2) y<0

x-y+1 > x+y-1
1-y > y-1
2y < 2
y < 1

1) does not talk about x. Insufficient
2) implies y<1.
Sufficient

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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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01 Oct 2010, 07:46
shrouded1 wrote:
Michmax3 wrote:
Is x-y+1 greater than x+y-1

1) x>0
2) y<0

x-y+1 > x+y-1
1-y > y-1
2y < 2
y < 1

1) does not talk about x. Insufficient
2) implies y<1.
Sufficient

Morning!

I'm just beginning to study for the GMAT and have a very weak quant background. I answered this question correctly but it took me 5 minutes to do so. I need to find ways to save time, could you explain to me why you noted that "1) does not talk about x. Insufficient" ? It seems like you removed choice A quickly.

This is probably a terribly novice question but I'm a novice so, I hope you don't mind!

Cheers,
f
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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01 Oct 2010, 08:10
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fronds wrote:
shrouded1 wrote:
Michmax3 wrote:
Is x-y+1 greater than x+y-1

1) x>0
2) y<0

x-y+1 > x+y-1
1-y > y-1
2y < 2
y < 1

1) does not talk about x. Insufficient
2) implies y<1.
Sufficient

Morning!

I'm just beginning to study for the GMAT and have a very weak quant background. I answered this question correctly but it took me 5 minutes to do so. I need to find ways to save time, could you explain to me why you noted that "1) does not talk about x. Insufficient" ? It seems like you removed choice A quickly.

This is probably a terribly novice question but I'm a novice so, I hope you don't mind!

Cheers,
f

After manipulating the question stem (subtracting x on both sides) we are only left with y to determine...since Statement 1 gives x but says nothing about y, which is what we are looking for it is immediately insufficient
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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01 Oct 2010, 09:06
Michmax3 wrote:

After manipulating the question stem (subtracting x on both sides) we are only left with y to determine...since Statement 1 gives x but says nothing about y, which is what we are looking for it is immediately insufficient

Ah, I see that now. I need to notice the significance of things like this more quickly. Thank you for the answer.
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x – y + 1 greater than x + y – 1 [#permalink]

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17 Mar 2012, 23:13
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Is x – y + 1 greater than x + y – 1?
(1) x > 0
(2) y < 0

I saw a reply somewhere that simplifies the given equation as:
x – y + 1 > x + y – 1 (Canceling xon both sides)
y < 1

But my question is how we can cancel x as we don't know whether x is positive or negative?
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Re: x – y + 1 greater than x + y – 1 [#permalink]

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17 Mar 2012, 23:23
Two things :

1) I think you're thinking on lines of multiplying/dividing by x for inequalities, which can be done without flipping inequality sign only when we know whether the number is positive.

2) Even if the sign of x is not given, you know that on both sides of inequality the sign of x is same so you can cancel that out.
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Re: x – y + 1 greater than x + y – 1 [#permalink]

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17 Mar 2012, 23:37
subhashghosh wrote:
Two things :

1) I think you're thinking on lines of multiplying/dividing by x for inequalities, which can be done without flipping inequality sign only when we know whether the number is positive.

2) Even if the sign of x is not given, you know that on both sides of inequality the sign of x is same so you can cancel that out.

Subhash .. thanks for your reply .. Does this mean that we need to consider the positive/negative scenario ONLY in case we are multiplying/dividing the equation by a variable? So in this case, we dont need to consider the positive/negative scenario.
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Re: x – y + 1 greater than x + y – 1 [#permalink]

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17 Mar 2012, 23:40
Subhash .. thanks for your reply .. Does this mean that we need to consider the positive/negative scenario ONLY in case we are multiplying/dividing the equation by a variable? Yes, in case of inequalities, for equalities it doesn't matter.

So in this case, we dont need to consider the positive/negative scenario. No
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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30 Apr 2012, 08:48
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Is x-y+1 greater than x+y-1 ?

(1) x > 0
(2) y < 0
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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30 Apr 2012, 08:58
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Is x-y+1 greater than x+y-1 ?

Is x-y+1>x+y-1? --> x's cancel out and we get: is 2>2y? --> is y<1?

(1) x > 0. Not sufficient.
(2) y < 0. The answer to the question is YES. Sufficient.

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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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01 Dec 2013, 06:28
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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01 Sep 2014, 09:52
Hi Bunuel,

y<1 can also mean y=0 right.. how can we assume y<1 is equal to y<0?
please clarify if i am missing some point..
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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01 Sep 2014, 09:55
janani28 wrote:
Hi Bunuel,

y<1 can also mean y=0 right.. how can we assume y<1 is equal to y<0?
please clarify if i am missing some point..

The question asks whether y is less than 1. The second statement says that y is a negative number, so it must be less than 1.

Does this make sense?
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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01 Sep 2014, 09:58
yeah.. my bad...got the point ... thanks much
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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10 Apr 2015, 00:08
Bunuel wrote:
Is x-y+1 greater than x+y-1 ?

Is x-y+1>x+y-1? --> x's cancel out and we get: is 2>2y? --> is y<1?

(1) x > 0. Not sufficient.
(2) y < 0. The answer to the question is YES. Sufficient.

Hi Bunuel,

Can we cancel out x in this inequality. we dont know whether x is positive or negative. pls help.

Thanks,
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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10 Apr 2015, 00:12
CKG wrote:
Bunuel wrote:
Is x-y+1 greater than x+y-1 ?

Is x-y+1>x+y-1? --> x's cancel out and we get: is 2>2y? --> is y<1?

(1) x > 0. Not sufficient.
(2) y < 0. The answer to the question is YES. Sufficient.

Hi Bunuel,

Can we cancel out x in this inequality. we dont know whether x is positive or negative. pls help.

Thanks,

My Bad, Got confused. we can add or subtract anything form the inequalities and hence X cancels out !!
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27 Oct 2015, 06:43
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Re: Is x-y+1 greater than x+y-1 ? [#permalink]

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28 Oct 2015, 19:58
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Is x-y+1>x+y-1?

On rearranging the variables,
we get 2>2y? or simply y<1?

Hence our new question stem becomes: Is y less than 1?

Statement 1: x > 0. No information about y. NOT SUFFICIENT
Statement 2: y < 0. From this, we can safely say that y will be less than 1
SUFFICIENT

Option B
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Re: Is x-y+1 greater than x+y-1 ?   [#permalink] 28 Oct 2015, 19:58

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